The invention relates to a device for forming store units from a thread supplied from a yarn packet, in which the store units are successively laid onto a carrying surface and there temporarily are enclosed between a back and a front limiting means, as seen in the supply direction, said limiting means being adapted to assume alternately with a phase shift an operative and an inoperative position, such that each time when the front limiting means assumes the inoperative position, the front store unit is released for being drawn from the carrying surface, and the next store unit assumes the position of the released store unit.
Such a device is e.g. known from U.S. Pat. No. 4,132,370. In this known device which is designed for intermittently feeding the weft transporting device of a shuttleless weaving machine, the carrying surface is part of a winding drum onto which the thread store units are laid through the intermediary of a rotating winding arm in the shape of thread windings. The limiting means are therein constituted by pins carrying out a translation movement in a plane containing the axis of the winding drum, such that said pins successively move outwardly from the space within the drum and at the release end of the drum are again retracted. As soon as the front limiting pin is retracted into the space within the drum the store winding which was up till that moment confined behind said pin is drawn by the weft transporting device of the weaving machine, while the store winding which is formed behind the next limiting pin is moved towards the drawing off end of the drum in order to be released during the next weft phase of the weaving machine for being drawn off.
A disadvantage in such a device is that the last part of a thread store winding, which has been released for being drawn off, is suddenly drawn taut at the end of the drawing off movement around the next limiting pin (which constitutes the front limiting pin for the next store unit) which causes a pull on the thread. Thereby tension peaks may be generated which may lead to thread failure.
The invention aims at removing this disadvantage.